1. Field of the Invention
This invention relates to tank fill valves, and more particularly, to a snap-action piloted fill valve useful for controlling the fluid level in a tank such as those used as water reservoirs for conventional toilets.
2. Description of Related Art
Fill valves using floats disposed inside housings are well known in the art, being disclosed for example in U.S. Pat. Nos. 6,003,541 and 5,638,859. U.S. Pat. No. 6,003,541 discloses a storage tank fill valve having a float arm which opens and closes a pilot orifice in a diaphragm valve. U.S. Pat. No. 5,638,859 discloses a float disposed within a cylindrical float chamber, with a pivotable arm connecting the float to the valve. Valve shuttle means are disclosed for controlling fluid flow from the float chamber in response to the movement of the float and pivotable arm.
Snap action piloted fill valves are also previously known. U.S. Pat. No. 4,248,402, for example, discloses a valve with a heating element that is energized to cause a bimetal disc to snap over-center between open and closed valve positions.
Other pilot and fill valve assemblies are disclosed in U.S. Pat. Nos. 2,572,175; 3,955,791; 3,895,645; 4,561,627; 4,646,779; 5,067,516; 5,191,912; 5,715,859 and 5,836,346.
The piloted fill valve disclosed herein has a unique structure and snap-action operation that causes the valve to be either fully open or fully closed. The valve preferably comprises a float and a weight cup that are interconnected by an elongated sleeve slidably disposed on a stem extending upwardly from a valve body mounted in a tank. Rising liquid inside the tank causes the float to slide upwardly on the stem, also pulling the weight cup upwardly. As the liquid level inside the tank approaches the desired fill level, the float pulls the sleeve and weight cup upwardly relative to the valve body. A substantially rigid link between the weight cup and a snap-action beam connected to the valve body is tightened as the weight cup rises relative to the valve body, causing the beam to move through an over-center position, which closes the pilot and thereby also closes the fill valve. When the tank is drained or flushed, the float, sleeve and weight cup slide downwardly on the stem, and the weight of liquid retained in the weight cup causes the beam to snap downwardly through its over-center position as the liquid level in the tank drops to a predetermined level, thereby opening the pilot and the fill valve, and permitting the tank to refill. The float, sleeve and weight cup are designed so that their combined weight is insufficient to snap the beam back through its over-center position to open the pilot and fill valve until the tank drains to a predetermined level. The vertical separation between the float and the weight cup is preferably adjustable to permit selective control over the liquid level at which the fill valve closes. The operation of the snap-action beam is desirably sudden and definite as it opens and closes the pilot, avoiding dribbling or partial flow during the change of position.
According to one embodiment of the invention, a piloted fill valve is disclosed that comprises a single elastomeric member useful as a seal for the pilot, as a diaphragm for the fill valve, and optionally, as a seal for a vacuum breaker.
According to another embodiment of the invention, the position of the float relative to the weight cup is manually adjustable using threads or detent members that selectively position the float at a desired height on the elongated sleeve.